JP2009114224A - Liquid crystalline polyester resin composition - Google Patents

Abstract

Disclosed is a liquid crystalline polyester resin composition having good releasability from a mold during molding and further improved heat resistance.
SOLUTION: To 100 parts by weight of a liquid crystalline polyester resin, a tetraester of pentaerythritol and a higher fatty acid having 10 to 32 carbon atoms having an acid value of 0.01 to 0.5 and a hydroxyl value of 0.01 to 5 is 0.001. Add 1 part by weight.
[Selection figure] None

Description

  The present invention relates to a liquid crystalline polyester resin composition having good mold releasability during molding and further improved heat resistance.

  In recent years, highly heat-resistant thermoplastic resins have been required for electrical / electronic equipment component materials, automotive equipment component materials, chemical equipment component materials, and the like. A liquid crystalline polyester resin is one of the resins that meet this requirement. However, the liquid crystalline polyester resin has a small shrinkage rate when solidified from a molten state and has a good fluidity, so that it is often applied to a precision molded product. However, because there are many molds with complex shapes, the mold release from the mold is bad during molding, stable continuous molding is difficult, molding speed (molding cycle) is slow, and productivity is poor. Has a dot. Although the liquid crystalline polyester resin is a resin having a better release property than other resins, the release property is still unsatisfactory in the above situation.

Conventionally, as a releasability improving method, a method of adding a releasability improving agent to a resin is generally used. The following are known as the releasability improver.
(1) Addition of fatty acid metal salt such as zinc stearate and lithium stearate (2) Addition of fatty acid ester such as glycerol tristearate (3) Fatty acid amide such as N, N'-alkylenebisalkanamide However, in any of the methods (1), (2), and (3), although the thermal decomposition temperature of the mold release improver is lower than the molding temperature of the liquid crystalline polyester resin, the mold release effect is recognized, but the mold release effect is observed. There are problems such as discoloration of the molded product due to decomposition of the mold property improving agent, deterioration of mechanical properties, generation of gas during kneading and molding, and the like.

In order to improve such a problem, Patent Document 1 proposes blending a specific higher fatty acid ester.
Japanese Patent No. 2915915

  According to the method of Patent Document 1, the releasability from the mold is improved without problems such as gas generation. However, in recent years, the use environment of liquid crystalline polyester resins has become more severe, and more heat resistance has been required. In order to meet the demand, liquid crystal polyester resin having a higher melting point was used, but with this, the processing temperature also increased, heat resistance at higher temperature was required, and the release agent of Patent Document 1 is sufficient It is no longer satisfactory.

  As a result of studies conducted by the present inventors to maintain good releasability and improve the heat resistance of the liquid crystalline polyester resin composition at high temperatures, it is found that the use of a specific high purity fatty acid tetraester is extremely effective. As a result, the present invention has been completed.

  That is, the present invention relates to a tetraester of pentaerythritol and a higher fatty acid having 10 to 32 carbon atoms, having an acid value of 0.01 to 0.5 and a hydroxyl value of 0.01 to 5, based on 100 parts by weight of the liquid crystalline polyester resin. A liquid crystalline polyester resin composition comprising 0.001 to 1 part by weight of an ester.

  The liquid crystalline polyester resin used in the present invention (hereinafter, the resin may be omitted) refers to a melt processable polymer having a property capable of forming an optically anisotropic molten phase. The property of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, the anisotropic molten phase can be confirmed by observing a molten sample placed on a Leitz hot stage at a magnification of 40 times in a nitrogen atmosphere using a Leitz polarizing microscope. When the liquid crystalline resin applicable to the present invention is inspected between crossed polarizers, polarized light is normally transmitted even in a molten stationary state, and optically anisotropic.

  The liquid crystalline polyester as described above is not particularly limited, but is preferably an aromatic polyester or an aromatic polyester amide, and also includes an aromatic polyester or a polyester partially containing an aromatic polyester amide in the same molecular chain. It is in. They preferably have a logarithmic viscosity (IV) of at least about 2.0 dl / g, more preferably 2.0-10.0 dl / g when dissolved in pentafluorophenol at 60 ° C. at a concentration of 0.1% by weight. .) Are used.

  The aromatic polyester or aromatic polyester amide as the liquid crystalline polyester applicable to the present invention is particularly preferably at least one compound selected from the group of aromatic hydroxycarboxylic acids, aromatic hydroxyamines, and aromatic diamines. Aromatic polyesters and aromatic polyester amides as constituent components.

More specifically,
(1) A polyester mainly composed of one or more aromatic hydroxycarboxylic acids and derivatives thereof;
(2) mainly (a) one or more of aromatic hydroxycarboxylic acids and derivatives thereof; and (b) one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof; c) Polyester comprising at least one or more of aromatic diol, alicyclic diol, aliphatic diol and derivatives thereof;
(3) mainly (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof; (b) one or more aromatic hydroxyamines, aromatic diamines and derivatives thereof; and (c). A polyesteramide comprising one or more of aromatic dicarboxylic acid, alicyclic dicarboxylic acid and derivatives thereof;
(4) mainly (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof; (b) one or more aromatic hydroxyamines, aromatic diamines and derivatives thereof; and (c). One or more of aromatic dicarboxylic acid, alicyclic dicarboxylic acid and derivatives thereof; and (d) at least one or more of aromatic diol, alicyclic diol, aliphatic diol and derivatives thereof, and The polyesteramide which consists of, etc. are mentioned. Furthermore, you may use a molecular weight modifier together with said structural component as needed.

  Specific examples of the specific compound constituting the liquid crystalline polyester applicable to the present invention include p-hydroxybenzoic acid, aromatic hydroxycarboxylic acids such as 6-hydroxy-2-naphthoic acid, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl, hydroquinone, resorcin, aromatic diols such as compounds represented by the following general formula (I) and the following general formula (II); terephthalic acid, isophthalic acid, 4 , 4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid and aromatic dicarboxylic acids such as compounds represented by the following general formula (III); aromatic amines such as p-aminophenol and p-phenylenediamine Can be mentioned.

(However, X: alkylene (C1 -C4), alkylidene, -O-, -SO -, - SO 2 -, -S -, - CO- than group _{selected, Y :-( CH 2) n -} (n = 1~4), - O (CH 2) n O- (n = 1~4) from the group selected)
Particularly preferred liquid crystalline polyesters to which the present invention is applied include aromatic polyesters containing p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4,4′-dihydroxybiphenyl, and terephthalic acid as main structural unit components. is there.

  Further, among liquid crystalline polyester resins, the intended effect is remarkable in a liquid crystalline polyester resin called type I having a relatively high melting point.

  The fatty acid ester used in the present invention is a tetraester of pentaerythritol and a higher fatty acid having 10 to 32 carbon atoms, which is a fatty acid ester having an acid value of 0.01 to 0.5 and a hydroxyl value of 0.01 to 5, preferably Higher fatty acids having 14 to 26 carbon atoms, pentaerythritol tetrastearate and pentaerythritol tetrabehenate are particularly preferably used.

  The acid value in the present invention can be measured by a known method. For example, a method is generally used in which a sample is dissolved in a benzene-ethanol mixed solvent and titrated with a potassium hydroxide solution having a known titer. . The acid value in the present invention is 0.01 to 0.5, preferably 0.3 or less. When the acid value exceeds 0.5, the thermal deterioration of the resin is accelerated when blended with a liquid crystalline polyester resin.

  The hydroxyl value in the present invention can be measured by a known method. For example, the sample is heated with an excess of an acetylating agent, for example, acetic anhydride, acetylated, and the saponified value of the produced acetylated product is measured. Calculate according to the following formula:

Hydroxyl value = A / (1-0.00075A) -B
Here, A represents a saponification value after acetylation, and B represents a saponification value before acetylation.

  The hydroxyl value in this invention is 0.01-5, Preferably it is 4 or less.

  When the hydroxyl value exceeds 5, the thermal deterioration of the resin is accelerated when blended with a liquid crystalline polyester resin, which is not preferable.

Next, the liquid crystalline polyester resin of the present invention can be blended with various fibrous, powdery, and plate-like inorganic fillers according to the purpose of use.
Examples of the fibrous filler include glass fiber, asbestos fiber, silica fiber, silica / alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, titanium, Examples thereof include inorganic fibrous materials such as metallic fibrous materials such as copper and brass.

On the other hand, powder fillers include carbon black, graphite, silica, quartz powder, glass beads, milled glass fiber, glass balloon, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, and wollastonite. Silicates such as silicate, iron oxide, titanium oxide, zinc oxide, antimony trioxide, oxides of metals such as alumina, carbonates of metals such as calcium carbonate and magnesium carbonate, sulfates of metals such as calcium sulfate and barium sulfate, etc. Examples thereof include ferrite, silicon carbide, silicon nitride, boron nitride, and various metal powders.
Examples of the plate-like filler include mica, glass flakes, various metal foils and the like.

  These inorganic fillers can be used alone or in combination of two or more.

  In using these fillers, it is desirable to use a sizing agent or a surface treatment agent if necessary. Examples of this are functional compounds such as epoxy compounds, isocyanate compounds, silane compounds, and titanate compounds. These compounds may be used after surface treatment or convergence treatment in advance, or may be added at the same time as material preparation.

  The amount of the inorganic filler to be used is 500 parts by weight or less, preferably 0.5 to 500 parts by weight, particularly preferably 5 to 250 parts by weight, per 100 parts by weight of the liquid crystalline polyester resin. If the amount is more than 500 parts by weight, the fluidity is lost, and particularly in the case of a mold having a complicated shape, the molding operation becomes difficult. Further, if it is excessive, the resin becomes brittle, and the mechanical strength of the molded product also becomes a problem.

  Furthermore, the composition of the present invention generally contains known substances generally added to thermoplastic resins and thermosetting resins, that is, stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents, flame retardants, dyes, Colorants such as pigments can be added as appropriate according to the required performance.

  The liquid crystalline polyester resin composition of the present invention can be prepared by equipment and methods generally used for preparing synthetic resin compositions. In other words, the necessary components can be mixed, kneaded using a single or twin screw extruder, extruded to form pellets for molding, and a part of the necessary components can be mixed and molded as a master batch, or each component In order to improve the dispersion and mixing, part or all of the liquid crystalline polyester resin may be pulverized, mixed and melt extruded.

  EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to these examples.

Examples 1-2
Liquid crystalline polyester (polyplastics Co., Ltd., Vectra S950) and glass fiber in the amount shown in Table 1 (Nippon Electric Glass Co., Ltd., glass chopped strand ECS 03 T-786H), talc (Matsumura Sangyo Co., Ltd.) , Crown talc PP), fatty acid ester B-1 (pentaerythritol tetrabehenate, manufactured by Nippon Oil & Fats Co., Ltd., Nissan Electol WEP-5) or B-2 (pentaerythritol tetrastearate, Nippon Oil & Fats Co., Ltd.) ) And Nissan Electol WEP-6) were mixed and then melt-kneaded at a cylinder set temperature of 365 ° C. in a 44 mm twin screw extruder (manufactured by Nippon Steel Works, TEX-44) to form a pellet. Then, the obtained pellet was evaluated by the method shown below. The results are shown in Table 1.

Comparative Examples 1-2
As a comparative example, when fatty acid ester was not used (Comparative Example 1), B-3 (pentaerythritol tetrastearate, manufactured by Cognis Japan, LOXIOL VP861) having a high acid value and hydroxyl value was used as the fatty acid ester. In this case, pellets were prepared and evaluated in the same manner as in the examples. The results are shown in Table 1.

[Acid value / hydroxyl value of fatty acid]
Measurements were performed according to JIS K0070.
[Bending test]
Based on ISO178, bending strength, bending elastic modulus, and bending strain at break were measured.
[Blister test]
A test piece for blister evaluation having a length of 124 mm, a width of 12 mm, and a thickness of 0.8 mm was molded under the following conditions.
・ Molding condition molding machine; SE100DU-C250M (manufactured by Sumitomo Heavy Industries)
Cylinder temperature: 370 ° C
Injection speed: 33mm / sec
Holding pressure: 70MPa
Injection holding time: 9 sec
Cooling time: 10 sec
Screw rotation speed: 100rpm
Screw back pressure: 4MPa
The obtained specimen was left in an oven at an arbitrary temperature for 5 minutes, and the surface was observed. The highest temperature at which the surface did not bulge was designated as Blister Free Temp (BFT). It can be said that the higher the temperature, the better the heat resistance.

[Release resistance]
The cap-shaped molded product shown in FIG. 1 was molded under the following conditions, and the peak pressure when the molded product was ejected was measured with an indirect pressure sensor to determine the mold release resistance.
・ Molding condition molding machine: FANUC ROBOSHOTα-50C (manufactured by FANUC)
Cylinder temperature: 370 ° C
Mold temperature: 80 ℃
Injection speed: 50mm / sec
Holding pressure: 50MPa
Injection holding pressure time: 5 sec
Cooling time: 10 sec
Screw rotation speed: 100rpm
Screw back pressure: 1MPa
Extrusion speed: 50mm / sec

It is a figure which shows the cap-shaped molded product used for mold release resistance evaluation by this invention, (a) is a side view, (b) is a top view.

Claims (2)

0.001 to 1 part by weight of a fatty acid ester having a tetraester of pentaerythritol and a higher fatty acid having 10 to 32 carbon atoms and having an acid value of 0.01 to 0.5 and a hydroxyl value of 0.01 to 5 to 100 parts by weight of a liquid crystalline polyester resin A liquid crystalline polyester resin composition comprising: The liquid crystalline polyester resin composition according to claim 1, wherein the fatty acid ester is pentaerythritol tetrastearate or pentaerythritol tetrabehenate.

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